In this paper,a novel BC3N2 monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations.The predicted structure meets the thermodynamical,dynamical,and mechanical stability requirements.Interestingly,the BC3N2 plane shows a metallic character.Importantly,BC3N2 has an in-plane stiffness comparable to that of graphene.We have also investigated the adsorption characteristics of CO2 on pristine monolayer and Mo functionalized monolayer using density functional theory.Subsequently,electronic structures of the interacting systems (CO2 molecule and substrates) have been preliminarily explored.The results show that Mo/BC3N2 has a stronger adsorption capacity towards CO2 comparing with the pristine one,which can provide a reference for the further study of the CO2 reduction mechanism on the transition metal-functionalized surface as well as the new catalyst\'s design.